US2804725A - Apparatus for precision contouring - Google Patents

Description

Sept. 3, 1957 E. c. DENcH APPARATUS FOR PRECISION coNTouRING 2 Sheets-Sheet l Filed May 17, 1954 5 n m E0 Ul T ma H M @N w y ma nNM N@ @N lil IIIIIIL Sept. 3, 1957 E. c. DENcH APPARATUS Foa PRECISION coNToURING 2 Sheets-Sheet 2 Filed May 17, 1954 APPARATUS FOR PRECISION CONTOURING Edward C. Dench, Needham, Mass., assigner to Raytheon Manufacturing Company, Waltham, Mass., a corporation of Delaware Application May 17, 1954, Serial No. 430,151

12 Claims. (Cl. 51-64) This invention relates to contoung, and particularly to fashioning hard or brittle material into desired shapes, `for performance of special functions as, for example, the function of insulating the cathode element in a radiant energy transmitter, such as a magnetron or the like.

The invention is characterized by the utilization of a vibratory `shaping tool and the activation of such tool in a manner to cause it to make an extremely great number of cutting strokes per second, with the impact force of successive cutting strokes being maintained at a relatively constant value, thus minimizing the risk of creating a fracturing or shearing stress within the material being worked upon.

By causing the cutting impacts to occur at constant force, and at a frequency of many thousands of impacts per second, the present invention makes it possible to cut through a hard or brittle piece of considerable thickness in a very few minutes and thus exceed the production rate of prior cutting methods while eliminating virtually all of the breakage risk inherent in the former methods.

The invention includes the application of an electromagnetic field to a magnetostrictive element having a cutting or shaping tool integrated therewith, to produce high frequency oscillation of the tool, and the feeding of such tool into the workpiece as the cutting or shaping operation proceeds. In two of the embodiments herein illustrated, the entire contour to be produced is incorporated in the cutting edge of the tool, Iso that there is no necessity to move the workpiece during the contouring operation. In a third illustrated embodiment, the workpiece undergoes continuous motion during the contouringoperation. In

all three embodiments, the tool is fed into the workpiece progressively as the contouring operation proceeds. In one embodiment the feeding is controlled electrically; in another, it is controlled by fluid pressure.

In the machining of relatively hard materials, the use of rapidly vibrated cutting tools has become increasingly popular. Primarily, the employment of extremely high oscillation frequencies makes it possible to achieve a substantial cutting effect with the application of precisely controlled impact force for each cycle of engagement of the tool with the material, thereby reducing greatly the likelihood of damage to the material, such las is more readily caused when the force applied is variable. This is particularly true where the material being worked is of a highly brittle character, as, for example, glass, porcelain, or other ceramic. On the other hand, if the attainment of the high frequency rate of oscillation is achieved by the employment of electromagnetic elements cooperating with magnetostrictive materials, there is an inherent limitation upon the vamount of electromotive force that can be introduced into the device and, hence, a corresponding limitation upon the degree of impact force which can be developed. For this reason, `su-ch tools have up to the present time been somewhat limited in their application and, accordingly, it has been impracticable to apply such high frequency drilling or cutting methods except where nited States Patenty O ICC the character of the opening or groove or other configuration to be formed has been such that its total cross-sectional area was relatively small.

The present invention makes it possible to apply electromagnetically driven high frequency vibratory tools to drilling or cutting operations wherein the article to be formed or fashioned out of a piece of relatively hard material has a total cross-sectional area many time.: larger than that which has been obtainable by the methods heretofore available. In this connection, a feature of the invention is the use of a tool having its cutting edge in the form of a circle or other yclosed loop corresponding in contour to the contour of the article to be fashioned out of a piece of stock, and with the transverse thickness of the cutting edge reduced to an extremely tine dimension, such as that commonly employed in cutting operations utilizing diamond-tipped tools. With such an arrangement, it is possible to fashion out of a piece of relatively hard material an article having a total cross-sectional area of many square inches, for example, by the use of the same type of electromagnetic vibratory driving means heretofore limited to the formation of slots, recesses, or other openings of a maximum cross-sectional area of only a few square centimeters at the most.

These and other characteristics of the invention will become apparent as the description thereof progresses, reference being had to the accompanying drawings where- 1n:

Fig. 1 illustrates apparatus constituting one embodiment of the invention;

Y Fig. 2 is an enlarged View of a fragment of the Fig. l assembly;

Fig. 3 illustrates a motor drive for the feeding of the o tool assembly of Fig. l;

Fig. 4 shows a second embodiment;

Fig. 5 shows a third embodiment; and

Fig. 6 shows electrical connections applicable to the embodiment of Fig. 5.

In Fig. l there is disclosed a machine suitable for practice of the invention, particularly in those situations wherein it is deemed desirable tovhave the fashioning tool operate along a horizontal axis, with the workpiece being held in a chuck or vise permitting the workpiece to be positioned along the same horizontal axis. As illustrated in Fig. 3, the machine includes a supporting frame 11 resting upon base anges 12 and having complementary sections 13 and 14 secured to each other by bolts 23 and adapted to receive the corresponding end sections 16 and 17 of an elongated tool holding cylinder 15 having longlead threads 18 disposed along the exterior surface for interengagment with corresponding threads formed internally of a centrally disposed gear 19 adapted to be rotated by a pinion 20 carried on a shaft 21 forming an extension of the armature shaft of a torque motor 22 more fully described hereinafter. The gear 19 (see Fig. l) is shown as provided with supporting rings 24 and 25 suitably secured to the gear 19 as, for example, by the use of through-bolts 27. These rings 24 and 25 are, in turn, rotatably supported upon ball-bearing assemblies 31 and 32 retained in suitable circular recesses formed in the elements 13 and 14, respectively. These el- ements 13 and 14 `of the frame are splined, as indicated at 36 and 37, respectively, for cooperation with corresponding splines formed upon the outer portion 16 of the tool housing 15, these splines permitting longitudinal feeding of the tool housing 15, and the tool itself, while at the same time holding the tool housing and to tool against any rotation or transverse `angular shifting with respect to the supporting frame. A flexible cover 2S attaches to a nut 29 threaded to the end portion 16, to protect the splines.

The action of motor 22 in continuously applying constant turning effort upon gear 19 (which gear is, in effect,

a lead screw) is translated into constant axially directed feeding pressure applied to the tool housing 15-hence constant tool impact force.

The tool proper is shown in Figs. 1 and 2 as including a supporting ring 41 adapted for quickattachmenttothe forward end of a tool actuator 40, an intermediate 4ring 44 set into a circular recess formed the forward face of the ring 41, and a cutting ring 46 having imbedded therein a multiplicity of diamond points lor equivalent means forming aY cutting edge for contact with the workpiece v47 mounted in the supporting chuck 49. lt will be understood that the cutting ring 46 is mounted within the ring 44 in such a manner as to present a thin circular line of contact with the workpiece 47, with the thickness of the cutting edge thus formed being conlined to Vthe smallest physical dimension compatible with the impact absorbing capacity of the material chosen for the purpose. lf necessary o'r desirable., the cuttingaction of the ring 46 maybe supplemented by the introduction of abrasive material entrainedkin a liquid stream supplied along the cutting larea by means `of a suitable `feedconduit and no'z'zle, not shown, in conformity with a technique that is well known in the art.V The tool housing 1S is provided with an inwardly directed boss 48 having engagement with thetool driving asesmbly at an antinode along the longitudinal axis of the assembly, which assembly illustrated as taking a form corresponding to `that illustrated in Fig. l of United States Patent No. 2,632,858, issued to Carlo L. Calosi on March 24, 1953.

As in said Calosi patent, the driving means includes a tapered actuator,n vor` oscillation -transmitter 40, and a magnetostrictive driver 39 in the form of a stack of thin laminae of nickei surrounded by coils 54 whose inner ends are interconnected, and whose outer ends Vare eX- tended, inthe formof leads 55 and 56,l to a current source to be further described. The laminae 39 undergo alternate expansions and contractions when suitably energized with polarizing direct current, combined with alternating current of the proper frequency. flfhefdriving means 39 operates at its natural frequency withconsiderable f orce and sets the vibratory `element 40 into vibration. Conveniently, the driving means 39 may have a length substantially equal to `one-half a wave length therein of oscillations at the operating frequency, while the vibratory element 40 may be any Vintegral number ofhalf wave lengths long, being illustrated herein as substantially 'one whole wave length; t An antinode exists in this vibratory system at the region where the driving means 39 is joined tothe vibratory element 40, The joining may be readily effected inv any suitable manner, as by silver soldering the interfaces of thetwo parts, for example. Adjacent the antinodal plane of joinde'r, the `drive trans'- mitter 40 is Vexternally threaded toreceive the internally threaded end `of a thin-walled cylindrical tube 48 of quater wave length, corresponding to the tube designated by numeral 15 in the Calosilpatent above identiiied. v As in said Calosi patent,the tube `48vterrninates at its other end in a relativelyrnassive lring 17 constituting, with its assocaited cylindrical housing element 15, a nonvib'ra'tory support corresponding to the `nonvibratory supporting ring 17 of the Calosi patent, 'exc'ep't that housing 15 is longitudinally movable.

For the reasons more fully explained in said Calosi patent, ring 17 absorbs no energy `from the vibratory system, being connected thereto at the antinodal plane of joinder of parts 39 and 4t).

Heat generated during energization of the magnetostrictive driver 39 is dissipated by cooling means (similar to that of the Calosi patent) in the form of a perforated tubular ring 91 supplied with cooling fluid under pressure by way of an inlet port 92 at one end of 'cylinder 15, there being an outlet passage 93 at the opposite end of the cylinder for removal of the fluid after it has been sprayed across the surfaces of thedriver 39, the coils 54, andthe tube 15 by the pressure acting thereon as the liuid emerges through the multiple openings 94- in the tubular ring 91.

The coils 54 are furnished with leads 55 and 56 which are brought through an opening in the end wall of cylinder 15. A rigid pipe 97 is affixed in this opening and extends part way into the housing 15. For the purpose of preventing water from leaking out through the pipe 97, a watertight cap 98 surrounds the leads 55 and 56, and seals off the inner end of the pipe.

Fig. 4 shows a second embodiment of the invention in which the cylinder 15 supporting the tool actuator 4t) and the tool driving means 39 is adapted to be moved forward along its longitudinal axis by uid pressure applied directly to the cylinder. In the form illustrated in Fig. 4, the cylinder is shown as provided with a transversely extending partition 101 intermediate its upper portion 102 and the body portion which surrounds the magnetostrictive driving means. The upper portion 102 is in the form of a cylindrical extension splined externally for engagement with the splines formed upon the stationary supporting section' 13, while the inner cylindrical surface of this extension is smooth-bored to receive 'the correspondingly machined outer cylindrical surface of a cylindrical abutment element 105 which is in effect a stationary piston having a centrally formed passageway 106 permitting introduction of iluid under pressure from a suitable source (not shown). Such source may include suitable pumping mechanism feeding into a fluid conduit 111 leading to said 'central passageway 106. Fluid under pressure thus introduced into the space between the stationary piston abutment and the transverse partition will exert a constantly acting pressure along the longitudinal axis of the tool carrier and vsuch pressure will operate to feed the tool forward into the material being worked upon. Suitable means are provided for securing the stationary piston abutment 105 to the :frame element 13. In the form illustrated in Fig. f4, such means includes a ange 116 and through-bolts 117 joining said ilange to the frame section 13, there being suitable fluid-sealing spacing elements 119 and 120 interposed between the ilange and the frame section, as indicated. To provide corresponding sealing means as between the stationary piston abutment and the cylindrical extension, one or more sealing rings 122 compressed yvithincircumferential grooves in the piston may also be provided. In this form of the invention it will be noted :that the entire outer surface of the main body portion of the cylinder may be `smoothly contoured as there is no necessity nforthe exterior threads illustrated in the first form of the invention.

Fig. 5 illustrates'another embodiment of the invention in which the cutting tool Ahas a solid cutting edge rather thanaclosed `loop contour, as in the embodiments heretofore described, and the desired contour is formed in the workpiece by moving the latter transversely of the longitudinal axis of cutting tool, the transversely moving means being illustrated 'as including a motion translating mechanisi'nqn the nform of a lead-screw 131 rotated by an electric motor 132 through suitable gear reduction mechanism 133, and an internally threaded carriage 134 constrained lby channel 136 to have rectilinear motion only. Carriage 134 has extending arms 135 constituting a chuck mechanism carrying radially movable workpiece engaging jaw elements '137 and 138 adapted to grip the workpiece 139 in the manner conventional in the art. The driving Vmotorl32 :may `be energized from a suitable source 'of current I141 (see 6) and the speed of rotation of the motor may be regulated by a shunt vfield cont'rol mechanism 143 `actuated by means 145 in circuit 144 connecting-A'. C. and D. C. sources 140 and 142, respectively, tocoils 54 of the magneto-'strietive driving means. Controller 14'5 Aoperates to relate the speed :of the motor to the frequency of loscillation of said 'magneto'strictive driving means, so that the lateral traverse of the workpiece 139 willbe proportional to the Vfrequency of vibration and, indirectly, 'to the rate lof-feed, of the tool. Also,

if desired, ,the control circuit for the motor may include suitable rotation reversing means 148 in the form of oppositely wound shunt field windings alternately operable at adjustable time intervals to cause the workpiece to effect a plurality of cycles of transverse motion in alternate directions as the tool reaches the opposite extreme positions defining the limits of the slot or other opening being formed in the workpiece, it being understood that the tool will also be fed forward progressively deeper into the workpiece on each successive traverse. Of course, as an alternate procedure, the motor 132 may drive unidirectionally, with reversals of the carriage 134 being effected by suitable mechanical linkage of conventional motion-reversing design.

This invention is not limited to the particular details of construction, materials and processes described, as many equivalents will suggest themselves to those skilled in the art. It is, accordingly, desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. In a cutting apparatus, a tool having a peripheral cutting edge of extreme thinness, said cutting edge forming a closed loop, means for vibrating said cutting edge at high frequency to cause said cutting edge to penetrate a piece of stock and thereby fashion out of said piece of stock an article having a contour conforming to that of said peripheral cutting edge, and means including interengaged long-lead helically threaded elements for exerting a constant feeding pressure upon said tool and thereby advancing said cutting edge through said piece of stock at a rate of advance which is proportional to the frequency of vibration.

2. In apparatus for establishing a desired contour in a piece of material, a workpiece supporting element, a tool supporting frame, a tool carrier having a hollow cylindrical extension externally splined for sliding support within said frame, said tool carrier including magnetostrictive driving means for causing said tool carrier to vibrate at high frequency along an axis normal to the plane of said workpiece, means operatively connected with said workpiece supporting element to cause said element to occupy progressively varying positions along the surface of said workpiece during operation of said magnetostrictive driving means, and means coacting with said iollow cylindrical extension for directing tool-feeding pressure axially of said tool carrier to maintain said tool Vin engagement with said workpiece.

3. In apparatus for establishing a desired contour in a piece of material, a workpiece supporting element, a tool supporting frame, a tool carrier mounted in said frame, said tool carrier including magnetostrictive driving means for causing said tool carrier to vibrate at high frequency along an axis normal to the plane of said workpiece, and means operatively connected with said workpiece supporting element to cause said element to occupy progressively varying positions along the surface of said workpiece during operation of said magnetostrictive driving means, said last-named means comprising motion translating mechanism including a relatively slowly rotating element, and means for rotating said last-named element in synchronism with the operation of said magnetostrictive driving means, said last-named means comprising an electric motor for driving said motion translating mechanism, a motor-energizing circuit including a variable resistor therein, a second circuit including means controlling the operating frequency of said magnetostrictive driving means, and linkage connecting said frequency-controlling means with said variable resistor.

4. In apparatus for establishing a desired contour in a piece of material, a workpiece supporting element, a tool supporting frame, a tool carrier mounted in said frame, said tool carrier including magnetostrictive driving meansfor causing said tool carrier to vibrate at high frequency along an axis normal to the plane of said workpiece, and means operatively connected with said workpiece supporting element to cause said clement to occupy progressively varying positions along the surface of said workpiece during operation of said magnetostrictive driving means, said last-named means including a prime mover drivably connected with said work supporting element to move the latter at a rate proportionate to the frequency of vibration of said tool carrier, and means for synchronizing the operation of said prime mover with the operation of said magnetostrictive driving means, said synchronizing means comprising a pair of inter-linked cir cuits, one of which constitutes energizing means for said magnetostrictive driving means, and the other of which constitutes energizing means for said prime mover.

5. In apparatus for forming an opening of a predetermined contour in a piece of material, in combination, a sup- .port for said piece of material, a tool engageable with the surface of said piece of material, magnetostrictive driving means for causing said tool to vibrate at high frequency along an axis common to said tool and magnetostrictive driving means, feeding means to cause said tool to penetrate progressively into said material, dynamo-electric means for shifting said material laterally of said axis, and means for synchronizing said shifting means with said feeding means, said synchronizing means comprising a pair of inter-linked circuits, one of which constitutes energizing means for said magnetostrictive driving means. and the other of which constitutes energizing means for said dynamo-electric means.

6. Apparatus for forming an opening of predetermined contour in a piece of material comprising, in combination, a tool engageable with said material, magnetostrictive driving means for operating said tool, means concentrically surrounding said driving means for supporting said driving means at a point of minimum vibratory amplitude, and means physically engaging said concentrically surrounding means to apply axially directed pressure c011- tinuously thereto for feeding said driving means and supporting means in a direction to cause said tool to penetrate progressively into said material.

7. Apparatus for forming an opening of predetermined contour in a piece of material comprising, in combination, a tool engageable with said material, magnetostrictive driving means for operating said tool, means concentrically surrounding said driving means for supporting said driving means at a point of minimum vibratory amplitude, means physically engaging said concentrically surrounding means to apply axially directed pressure continuously thereto for feeding said driving means and supporting means in a direction to cause said tool to penetrate progressively into said material, means for shifting said material laterally of said tool, and means for synchronizing the operation of said shifting means with that of said feeding means.

8. Apparatus for forming an opening of predetermined contour in a piece of material comprising, in combination, a tool engageable with said material, magnetostrictive driving means for operating said tool, means concentrically surrounding said driving means for supporting said driving means at a point of minimum vibratory amplitude, means physically engaging said concentrically surrounding means to apply axially directed pressure continuously thereto for feeding said driving means and supporting means in a direction to cause said tool to penetrate progressively into said material, means for shifting said material laterally of said tool, and means for synchronizing the operation of said shifting means with that of said driving means.

9. Apparatus for forming an opening of predetermined contour in a piece of material comprising, in combination, a tool engageable with said material, magnetostrictive driving means for operating said tool, means concentrically surrounding said driving means for supporting said driving means at a point of minimum vibratory amplitude, electrically-driven means physically engaging said concentrically surrounding means to apply axially directed pressure continuously thereto for feeding said driving means and supporting means in a direction to cause said tool to penetrate progressively into said material, means for shifting said material laterally of said tool, and means for synchronizing the operation of said shifting means with that of said feeding means.

10. Apparatus for forming an opening of predetermined 'contour in a piece `of material comprising, in cornbination, a tool engageable with said material, magnetostrictive driving means for operating said tool, means for supporting said driving means at a point of minimum vibratory amplitude, said supporting means including a cylindrical 'extension eoaxially aligned with said driving means, and fluid pressure operating means fitting operatively within said cylindrical extension for feeding said driving means and supporting means in a direction to cause said tool to penetrate progressively into said material.

l1. In a cutting apparatus, a penetrating tool having a magneto'strictive rod integrated therewith, carrier means operatively connected with said rod and tool to impart longitudinal feeding motion thereto in response to longitudinal motion of said carrier means, electrically driven motion-translating means concentrically surrounding said carrier means and operative to apply constant effort thereto for causing longitudinal motion of said carrier means, and electromagnetic means for imparting a high rate of vibration to said magnetostrictive rod to cause said penetrating tool to perform a cutting operation.

References Cited in the tile of this patent UNITED STATES PATENTS 724,706 Jones Apr. 7, 1903 1,380,869 Fay June 7, 1921 1,626,033 Furst Apr. 26, 1927 1,882,906 Renfer Oct. 18, 1932 2,296,819 Osgood Sept. 22, 1942 2,320,874 Lehmann `lune 1, 1943 2,412,211 Eichelman Dec. 10, 1946 2,452,211 Rosenthal Oct. 26, 1948 2,580,716 Balamuth Jan. 1, 1952 2,632,858 Calosi Mar. 24, 1953 2,651,148 Carwile Sept. 8, 1953 2,670,446 Turner Feb. 23. 1954

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